Technical Battery Size Question

The Odyssey batteries are very good. We had the best certified battery made for an aircraft and it constantly needed nursing. When the temperatures got down to zero you could just count the blades as it spun over. We thought maybe the starter was a problem. The battery was replaced with a pair of Odyssey batteries run in series to make 24v. Best thing ever for operating in the winter. The Odyssey cranked the engine over faster than we had seen before and when it got cold it did not affect the battery performance. We could fly out spend a day ice fishing with no worries over starting up to go home. The batteries required no nursing as they kept a good charge even if the plane did not move for months. The airplane was up for sale and a prospective buyer came to look at this past February when it was -10F. The engine spun over as always and started up immediately. The batteries were 4 years old. Odyssey claim that the batteries can be run flat, deliver power when its cold and will hold a charge for a long time without significant loss. The 2 Odyssey batteries were less than half the price of the certified 24V battery that they replaced.
We learned a thing about batteries and smart chargers. The "quality" aircraft battery went flat and the NOCO Genius couldn't recognize the battery. It took an old style charger to put enough power in the battery for the smart charger to work.

 

Odyssey’s have changed their part number systems. I still use them in our race cars but they are not as good as they were 15 years ago. One failed in my 2018 F150 in 1 year.

 

I have a keyed cut off switch in one of my battery cables AND a BatteryMinder 1500. Parasitic draw is not an issue.